London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
Paddington 1896
[Report of the Medical Officer of Health for Paddington, Borough of ]
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TABLE 34. Efficiency of Alteration, and fineness of sand.
| Amount of Storage (days' supply). | Average Rate of Filtration gal. per hour per sq. It. | Average Thickness of Sand on Filters. | Percentage of Sand, " fine.*' | Percentage of Organisms not removed.* | |
|---|---|---|---|---|---|
| Chelsea | 12.0 | 1.75 | 4.00 | 26.10 | 6.0 |
| West Middlesex | 5.6 | 1.25 | 2.75 | 78.19 | 2.5 |
| Grand Junction | 3.3 | 1.63 | 2.25 | 28.70 | 8.9 |
| New River | 4.4 | 2.29 | 1.80 | 60.26 | 2.2 |
| East London | 15.0 | 1.33 | 2.00 | 33.12 | 3.1 |
* Organisms in raw supply=100.
sand ror filtration. The "fine" sand passed through
a sieve of copper gauze with 1,600 meshes to the sq.
in., and the measure of its efficiency was the number
of organisms removed in filtration. It appears that
the Chelsea Company's 4 ft of sand, 26'10 per cent,
of which was " fine " sand, allowed 6.0 per cent, of the
microbes to pass through, whilst the l.8 ft. of sand
of the New River Company's filters, 60.26 of the sand
being "fine," allowed only 2.2 per cent, to get
through.
During June all the filters of all the Companies
were deranged, and the numbers of microbes in the
filtered waters were considerably in excess of the
standard. No cause for the derangemnt had been
discovered.
Mention may perhaps be made here of two
Reports which have been issued by the London